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1HZ, Injection Pump Knock

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1HZ, Injection Pump Knock

Gentlemen, and Ladies,
I am new to this forum, but have played with Engines and 4WDs for most of my life, (20 odd yrs). I have a 75 series Trayback, 1990 edition, with a stock 1HZ, having travelled ~280ks. I have small problem that very rapidly becomes nasty. Every so often and often just after starting when not used for a week, I get a rattle, knock type noise, from the Injection Pump. The noise is caused by the advancement piston in the IP, shuttling and striking the cover of the cover (which is down between the Engine and IP). This I know because if left long enough/allowed to continue and pushed/revved hard, a result can be to shear the bolts of the cover, dumping fuel out of the IP and then no go. Not good when driving along a busy road under the M4.
I have searched several forums, looking for answers nothing found.

I have two possible causes:
a.
If a small pocket of air was to enter the IP pump, would the internal pressure fluctuate enough to allow the advance piston to strike the cover??

Tried to disprove this theory by inverting the CAV filter, to ensure any air in the system was caught in the water (now air) bowl. The problem still exists, Bugger...

b.
This theory arises from a second question I'd like to ask, How much flow comes through the return line???
I happened to remove the return line and was quite surprised to find virtually zero flow, (maybe a few bubbles).
I understand that the IP body runs at about 100psi before the individual injection pumps. This pressure is controlled by a relief valve, under the return banjo fitting I believe.
My theory is this, if my Lift pump has failed or not providing sufficient flow, would it be possible for a vacuum to be drawn in the pump body?? If so what would be the result and remedy???
Is it possible to test the internal Pressure some how??

I have only heard of one other case similar, was a 12HT motor which only ever leaked fuel, other than that nothing...

I'm an engineer by trade, working in the forklift industry, used to engines and systems.

Thanks for your help.

Axel

Unread postby Axel » December 4th, 2007, 11:27 pm


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Axel wrote:b.
This theory arises from a second question I'd like to ask, How much flow comes through the return line???
I happened to remove the return line and was quite surprised to find virtually zero flow, (maybe a few bubbles).
I understand that the IP body runs at about 100psi before the individual injection pumps. This pressure is controlled by a relief valve, under the return banjo fitting I believe.
My theory is this, if my Lift pump has failed or not providing sufficient flow, would it be possible for a vacuum to be drawn in the pump body?? If so what would be the result and remedy???
Is it possible to test the internal Pressure some how??


You should have a decent flow from the return line, certainly more than some bubbles at idle and increasing with engine rpm. The pump should return more fuel than it actually sends to the injectors as it's this that lubes and cools the pump.

The internal pressure also controls the timer advance as you eluded to. The transfer pump sucks the fuel from the tank, through the filter and the relief valve in the front top corner of the pump controls the pressure. I believe you can install a gauge to check pressures however I've never done it.

I'd suggest that if your pick up screen in the tank is clean, the filter is clean (i.e. no restriction) then the transfer pump is crook or it's sucking air. Temporarily install some clear plastic tube between the filter and pump and check for bubbles. You could also temporarily install a vacuum gauge in that line to ensure there's no restriction, although you'll really need to load it up (drive ot dyno) to be able to check properly.

Let us know what you find.
Greg G.
2000 HDJ105 ~ 1HD-FT I/C TD

Unread postby HDJ105 » December 5th, 2007, 8:59 am


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The overflow should be as much as 900cc a minute at 2000 rpm(53 litres an hour). The FSM says there is an overflow screw and a relief valve that can be adjusted but as Greg said,your gonna need gauges and be able to spin the pump at operating speed

The pumps on these are not the best fuel pumps ever made and many need a rebuild around 200000. They wear out quicker than all the other rotary pumps.
The timer pump rattling is a good indication it is worn,probably wear in the housing as well

It just works out easier to dump it at a good diesel shop and let them do it.
Because they do so many the price is usually competitive and not much variation(still not cheap though).
1995 HZJ75 tray;)
1988 FJ73 with 1HZ conversion:cool:
1988 Volvo 740 GL :D

Unread postby roscoFJ73 » December 5th, 2007, 4:58 pm


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Quote:

"It just works out easier to dump it at a good diesel shop and let them do it.
Because they do so many the price is usually competitive and not much variation(still not cheap though).
"

Thanks fellas,
Every pump has different issues of course, but any idea of what sort of price range to expect, or who in Sydney is worth their going to??

Axel

Unread postby Axel » December 5th, 2007, 9:53 pm


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Location: perth wa

Axel wrote:Quote:

"It just works out easier to dump it at a good diesel shop and let them do it.
Because they do so many the price is usually competitive and not much variation(still not cheap though).
"

Thanks fellas,
Every pump has different issues of course, but any idea of what sort of price range to expect, or who in Sydney is worth their going to??

Axel


They can run into $1600. I think Ballarat Toyota was doing them new for under 2k
Mine was pretty worn out,I got it with a pile of other stuff. It ended up needing a whole new housing,dist head,plunger and some other parts and with labour came to $1550.
As you say every pump has different issues.
Im in Perth so I dont know Sydney diesel shops.
1995 HZJ75 tray;)
1988 FJ73 with 1HZ conversion:cool:
1988 Volvo 740 GL :D

Unread postby roscoFJ73 » December 6th, 2007, 10:28 am



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